Christopher C. Payne

Cytoplasmic polyhedrosis virus classification by electropherotype; validation by serological analyses and agarose gel electrophoresis.

Serological analyses of several different cytoplasmic polyhedrosis viruses (CPVs), including two type 1 CPVs from Bombyx mori, type 1 CPV from Dendrolimus spectabilis, type 12 CPV from Autographa gamma, type 2 CPV from Inachis io, type 5 CPV from Orgyia pseudotsugata and type 5 CPV from Heliothis armigera, demonstrated a close correlation between the antigenic properties of the polyhedrin or virus particle structural proteins and the genomic dsRNA electropherotypes. The dsRNAs of these viruses were analysed by electrophoresis in 3% and 10% polyacrylamide gels with a discontinuous Tris-HCl/Tris-glycine buffer system or by 1% agarose gel electrophoresis using a continuous Tris-acetate-EDTA buffer system. Electrophoretic analysis in agarose gels was found to be the most suitable for the classification of CPV isolates into electropherotypes, and the results obtained showed a close correlation with the observed antigenic relationships between different virus isolates. However, electrophoretic analysis in 10% polyacrylamide gels was most sensitive for the detection of intra-type variation and the presence of mixed virus isolates.

The Comparative Susceptibility of the Diamondback Moth Plutella xylostella and Some Other Major Lepidopteran Pests of Brassica Crops to a Range of Baculoviruses

The susceptibility of larvae of the Diamondback moth (DBM), Plutella xylostella to infection by three baculoviruses was evaluated in the laboratory using a microdroplet feeding assay. The viruses tested were a granulovirus (GV), originally isolated in Taiwan from P. xylostella larvae (Px GV-Taiwan); the nucleopolyhedrovirus (NPV) from Galleria mellonella (Gm NPV), and the NPV from Autographa californica (Ac NPV). Neonate P. xylostella larvae were susceptible to infection by all three viruses. In an extensive series of bioassays carried out over a 21-month period, LD 50S for neonate DBM larvae ranged from 1.0-8.9 viral occlusion bodies (OB) for Px GV-Taiwan, and 9.5-30.2 OB for Gm NPV and Ac NPV. LT 50S for the three viruses ranged from 3.8-6.0 days at 27 C, with Gm NPV having a significantly shorter LT 50 than the other two viruses. Second and third instar larvae of P. xylostella were significantly less susceptible to infection by Px GV-Taiwan (LD 50 s ranging from 18-57 OB/larva) than were neonate larvae...

Biochemical Properties of Polyhedra and Virus Particles of the Cytoplasmic Polyhedrosis Virus of Bombyx mori

The structural polypeptides of polyhedra and virus particles of the cytoplasmic polyhedrosis virus (CPV) of Bombyx mori L. were examined by PAGE. Five proteins were observed in polyhedra. The major polypeptide or ‘polyhedral protein’ had a molecular weight of 27,100 daltons and contained a covalently attached carbohydrate moiety. Virus particles extracted from polyhedra (‘occluded’ virions) had a density of 1.43–1.48 g/cm3 in CsCl, and contained five structural polypeptides. After prolonged storage at –20°, a further polypeptide was resolved. ‘Non-occluded’ virus particles had the same density, RNA components and structural proteins as ‘occluded’ virions.

Characterization and Cross-transmission of Baculoviruses Infectious to the Diamondback Moth, Plutella xylostella, and some other Lepidopteran Pests of Brassica Crops

Isolates of a granulovirus (GV) from the Diamondback Moth, Plutella xylostella, and nucleopolyhedrovirus (NPV) isolates from Galleria mellonella and Autographa californica were characterized by restriction endonuclease analysis of viral DNA. The capacity for these viruses to infect P. xylostella larvae and some other lepidopteran pests of brassica crops (including Heliothis virescens, Crocidolomia binotalis and Mamestra brassicae) was examined in cross-transmission experiments in which the DNA isolated from purified progeny viruses, was compared by restriction endonuclease analysis with DNA from the inoculum viruses. Two P. xylostella GV isolates from Taiwan and China (Px GV-Taiwan and Px GV-China) appeared to be very closely-related on the basis of comparative restriction endonuclease analysis of viral genomic DNA. However, both virus isolates could be distinguished by 1-3 major band differences and by sub-molar band variation when their DNA was analysed following digestion with Eco RI, Bam HI and Hin dI...

A radioimmunoassay for the cytoplasmic polyhedrosis virus from Bombyx mori.

Low titer antibodies to dsRNA were detected in an antiserum prepared to the cytoplasmic polyhedrosis virus from Bombyx mori. At antiserum dilutions between 1:320 and 1:20,480, more than 90% of intact

The Synthesis of Virus-Specific Single-Stranded RNA in Larvae of Bombyx mori Infected with a Cytoplasmic Polyhedrosis Virus

RNA synthesis in larvae of Bombyx mori was examined by theincorporation of 32P into purified single- and synthesis double-stranded RNAs. In larvae infected with a cytoplasmic polyhedrosis virus (CPV), both single- and double-stranded RNA were synthesized after pre-treatment with 10 µg actinomycin D. Approximately 70 % of the single-stranded RNA synthesized in these larvae re-annealed with heat-denatured RNA extracted from purified virions of B. mori CPV. It did not self-anneal, nor did it anneal significantly with RNA from Arctia caja CPV, or from B. morilaτvae. This suggested that the single-stranded RNA is largely virus-specific and represents viral messenger RNA.

Comparison of the virus-associated polymerases of cytoplasmic polyhedrosis virus types 1 and 2

A detailed comparison was made of the virus-associated polymerase activities of cytoplasmic polyhedrosis virus (CPV) types 1 and 2 which had previously been shown to differ in their response to the methyl donor S-adenosyl-L-methionine (AdoMet). While the type 1 CPV polymerase was approximately twice as active as the type 2 CPV enzyme in the presence of AdoMet, temperature, pH and divalent cation optima of the two enzymes were similar. Both viruses synthesized in vitro single-stranded RNA copies of only one strand of the double-stranded RNA genome. In addition, each RNA segment of both viruses was transcribed in approximately equal amounts by weight. The results suggest that most features of CPV polymerase activity are highly conserved, even among CPV types which show substantial antigenic and biochemical differences.